A cuff for providing compression to a limb

ABSTRACT

A cuff for providing compression to a limb, the cuff comprising an outer wall joined to an inner wall to form a bladder, the bladder being provided with means to separate the walls to maintain a path for fluid flow into and out of the bladder characterised in that the separating means are a spacer provided on the interior of at least one wall, which separates the walls when the bladder is deflated.

This invention relates to a compression device for the limb andparticularly to a device for use on the foot. The device is particularlysuited for use in the type of compression therapy used in the treatmentof venous foot ulcers or venous heel ulcers.

BACKGROUND OF THE INVENTION

Various compression devices are known for applying compressive pressureto a patient's limb. These types of devices are used to assist mainly inthe prevention of deep vein thrombosis (DVT), vascular disorders and thereduction of oedema. Prior art devices are adapted for use in a hospitalsetting in which they are used predominantly for the prevention of DVTin patients with a high risk for developing the same. U.S. Pat. Nos.5,117,812, 5,022,387 and 5,263,473 (The Kendall Company), U.S. Pat. No.6,231,532 (Tyco International Inc.), U.S. Pat. No. 6,440,093 (McEwen, etal.) and U.S. Pat. No. 6,463,934 (Aircast Inc.) disclose such devices.

Compression therapy is used in the treatment of venous leg ulcers. Thetreatment relies on the compression achieving a reduction in oedema andimproved return of blood via the venous system. This in turn reduces theresidence time for blood supplied to the lower limb and the severity ofischaemic episodes within the limb that can result in tissue breakdown.

Compression of the foot can be achieved by a pneumatic compressiondevice. The known devices apply pressure to the foot and to the rest ofthe limb through a thick cuff which is large, bulky and powered mainlyby electricity. The known devices not only affect patient mobility butare also aesthetically unacceptable to many patients. For instance thedevice can prevent the wearing of the patient's ordinary shoes andclothes meaning that the patient is housebound and unable to walk. Inthe hospital devices, these disadvantages are not apparent because thepatient is largely confined to bed.

A problem in providing an aesthetically acceptable foot cuff is one ofsupplying the pneumatic fluid to the cuff. In the hospital devices ofthe prior art, pneumatic fluid is supplied to the cuffs through anetwork of pipes without consideration to the patient being mobile,wearing normal clothing or wearing a shoe. Even if the patient is ableto put their shoe on with the cuff in place in a deflated state, theshoe may prevent inflation of the cuff in the areas where pressure isrequired as the shoe may block the path for the passage of pneumaticfluid. If a tube is used to supply the fluid to, for instance, the archof the foot, the shoe may collapse or kink the tube and may causepressure points on the foot.

In addition, a problem with the devices of the prior art is that thecuff is generally cylindrical and applies pressure over the whole of itssurface to the foot, meaning that the mobility of the ankle is reducedmaking walking difficult even if the patient can wear a shoe and inflatethe cuff.

Pneumatic compression devices do, however, have advantages in particularover compression bandages. They provide an effective treatment, whiledeflated, the inflatable cuff or cuffs are easy to apply to thepatient's foot and the pressure is more readily controlled andmonitored. Also, they are not subject to the effect of radius where thelevel of compression depends on the circumference of the limb so thathigh pressure and low pressure spots occur at the ankle where the radiusunder the bandage varies. The effect of radius is a fundamentallimitation of elasticated bandages and stockings. In addition, it isdifficult to apply pressure to the heel of the foot with an elasticbandage and this is an area in which ulcers occur. With elasticbandages, applying pressure to the heel means that mobility in the ankleis reduced as the bandage applies pressure over the whole ankle. Thisreduction in mobility impairs venous return as the patient is unable towalk normally.

There, thus, exists a need for a foot cuff, which focuses the pressureapplied by the cuff to those areas where ulcers are prevalent and limitsinflation of the cuff in the surrounding areas so that the patient isable to wear their ordinary shoes and clothes with the cuff inflated.There is also a need for a means of supplying pneumatic fluid to a footcuff so that inflation is focused on certain areas and the patient isallowed to be mobile and wear ordinary shoes without interrupting thesupply of fluid to the cuff. There is also a need for a foot cuff thatenables the application of pressure in a manner that is flexible enoughto allow the treatment of various indications from one device.

SUMMARY OF THE INVENTION

We have now invented a device for applying compression against apatient's foot which alleviates the above problems by providing a devicewhich is simple to apply to the foot, focuses pressure on certain areasof the foot, is low profile and lightweight and has a discreet pneumaticfluid supply. A first aspect of the present invention provides acompression device for the foot comprising:

-   -   a wrap adapted to surround the foot, the wrap comprising at        least two bladders which when inflated conform to the shape of        the foot to provide compression, the bladders being positioned        on the wrap so that a first bladder focuses compression on the        heel of the foot and a second bladder focuses compression on the        arch of the foot;    -   a channel attached to each bladder for independently delivering        fluid to each bladder; and    -   a controller attached to the channels that generates and        independently controls the flow of fluid to the bladders.

We have found that such a device may bring the advantages of applyingpressure to the heel and arch of the patient without reducing mobility.The pressure can also be targeted on the area of the heel where ulcersare most prevalent. Independent supply and control of fluid to twobladders means that the device can be operated in a number of ways. Thisflexibility enables a range of treatments to be provided by the deviceand, thus, allows one device to treat a number of different indications.

The device may be operated so that the pressures applied by the heel andarch bladders may be the same as or different from each other or may bethe same or different to the pressures applied by an associated device.The heel bladder, for example, may be at the same pressure as bladderslocated in an associated leg sleeve and may be attached thereto.

Preferably, the controller comprises a microprocessor control system anda pump. More preferably, the device comprises at least one pressuresensor in the channel or positioned in the device, the sensors providingreadings of the pressure experienced by the foot due to the inflation ofthe wrap by the controller.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view of the wrap of one embodiment of the presentinvention.

FIG. 2 is a perspective view of the heel part of another embodiment ofthe wrap of the invention.

FIG. 3 is a cross-sectional view on a plane horizontally through theankle of the patient and viewed from above with the device of FIG. 2 onthe foot showing the position of the heel bladder.

FIG. 4 is a perspective view of the first stage of applying the wrap ofFIG. 1 to a foot.

FIG. 5 is a perspective view of the second stage of applying the wrap ofFIG. 1 to a foot.

FIG. 6 is a perspective view of the final stage of applying the wrap ofFIG. 1 to a foot.

FIG. 7 is a cross sectional view taken on the line A-A of FIG. 1 showingthe spacing means in the channel.

FIGS. 8, 9 and 10 are perspective views of a low profile air channelaccording to another embodiment of the invention and in particularshowing the connection of a channel to a bladder.

DETAILED DESCRIPTION OF THE INVENTION

The wrap comprises two or more individually inflatable bladders. Thebladders may be formed from an outer wall and an inner wall, the innerwall contacting the foot in use. The wrap may comprise an inelasticfabric to which the bladders are fixed or the fabric may form the outerwall of the bladder. Preferably, the bladder walls are elastic and arejoined to the wrap by welding.

Preferably the bladder is provided with means to separate the walls inuse to maintain a path for fluid flow into and out of the bladder. Thishas the advantage that the inflation of the bladder may be localized tothe area of the foot where pressure needs to be applied, for instance,the heel and the arch of the foot, and may be limited in those areaswhere pressure need not be applied, for instance, the sides of the foot.In this way the patient is able to be mobile, has mobility in the ankleand may wear their ordinary clothes and shoes.

The separation means in the bladder may be an open foam materialpositioned between the bladder walls or may be a spacer provided on theinterior of at least one bladder wall. By this means it is not necessaryto have a tube supplying fluid running into the patient's shoe andcausing possible pressure points or blockages. The spacer is preferablymade from a flexible material that is relatively incompressible and iselongate to create a channel for the supply of fluid into and out of thebladder.

Preferably, the wrap has a Y-shaped outline when in an unwrapped state.One arm of the Y is provided with a bladder to apply pressure to theheel of the foot in use and the other arm of the Y is provided with abladder to apply pressure to the arch of the foot when in use. TheY-shaped wrap may be opened to a flat state making application to thepatient's foot easy enough that the patient may apply the deviceunaided.

The wrap may be applied to the foot by the patient placing the arch oftheir foot on the arch bladder located on one arm of the Y (the archarm) and with their heel in the fork of the Y. The tail of the Y maythen be wrapped over the top of the foot and the other arm of the Y (theheel arm) wrapped around the heel and fixed to the tail by loop and hookfastening. The free end of the arch arm is then folded over the top ofthe foot and attached to the heel arm and tail of the Y by hook and loopfastenings. Preferably the heel and arch bladders are located close tothe junction of the arms.

Alternatively, in another embodiment, the wrap may comprise a one strapfastening, fastened over the top of the foot, the heel and arch parts ofthe wrap being integral. The foot may be inserted in such a device andthe strap fastened over the instep.

The heel bladder is preferably divided into two parts which may beconnected and provides pressure in the areas between the malleoli andthe achilles on either side of the heel. This bladder can be permanentlyfixed in position on the wrap or can be repositionable to customise thefit to individual patients.

The wrap may be used in conjunction with a compression sleeve for thelower limb such as that described in GB 0307097.6 or GB 0423410.0. Whensuch a sleeve is present the wrap may be integral with it or beconnectable to it. The pressures applied by the heel and arch bladdersmay be the same or different from each other or may be the same ordifferent to the pressures in the cuffs of the sleeve.

The heel and/or arch bladders can connect directly to the controllerthat generates and controls the flow of fluid in the sleeve or canconnect to one of the bladders in the sleeve and, thus, be at the samepressure as that bladder or at different pressures.

Preferably, the channels connecting the heel and arch bladders to thesleeve or controller are low in profile and resistant to crushing orkinking for instance by the wearer's shoe. The channels may have asimilar construction to the bladder and comprise an outer wall and aninner wall in the form of elongate strips provided with means toseparate the walls in use to create a path for fluid flow from thesleeve or controller. In this way the separating means maintain a pathfor fluid flow despite crushing or kinking of the channel. Theseparation means in the channel can be the same as that used in thebladder and, preferably, is an elongate flexible strip, narrower thanthe width of the channel walls.

The channel walls are, preferably, made of the same material as thebladders and may be welded to a window in the bladder wall of the sleeveor wrap or cuff to make an air tight connection.

Preferably, there are one or more individual sensors associated witheach bladder to monitor the pressure from that bladder. This allows thecontroller to precisely control the pressure in that bladder and thedevice to comply with a predetermined pressure profile.

In a second embodiment, the invention provides a cuff for providingcompression to a limb, the cuff comprising an outer wall joined to aninner wall to form a bladder, the bladder being provided with a spacerto separate the walls to create a channel for fluid to flow into and outof the bladder.

The advantage of the cuff of the invention is that the separating meansallow the bladders to be shaped so that the compression generated by thedevice can be focused on those areas where ulcers are more prevalentwithout compromising the path for fluid movement.

The spacer is made from a relatively incompressible material that spacesthe walls apart but does not allow the bladder or channel to becomeobstructed in the manner that a tube may become obstructed by kinking orcollapsing or being flattened against, for instance, a shoe.

Preferably, the bladder walls are selectively welded together so thatinflation of the bladder is limited in the welded areas which can in usecontact those parts of the foot where compression is not required, forexample, the sides of the foot or over bony prominences in the heel.

The spacer is, preferably, provided on the inside of at least one wallof the bladder and, even more preferably, a spacer is provided on theinner wall of the bladder and a spacer is provided on the outer wall ofthe bladder which spacers abut when the bladder is deflated.

The spacers allow pneumatic fluid to flow into the bladders and have theadvantage that they are easily constructed on the bladder walls. Thespacers may be elongate and flexible so that the bladder may be shapedto provide an elongate channel for connection to a conduit of thedevice.

In a third embodiment, the invention provides a channel for connectingone or more bladders to each other or to a controller, the channelcomprising an elongate outer wall joined to an elongate inner wall, thechannel being provided with means to separate the walls to create a pathfor fluid to flow into and out of the channel.

The separating means are preferably a spacer provided on at least onewall of the channel and even more preferably a spacer provided on theinner wall of the channel and a spacer provided on the outer wall of thechannel which spacers abut when the channel is deflated.

Having spacers on opposing walls means that each spacer need only behalf the thickness of a single spacer on one wall yet achieve the sameseparation of the walls. This makes the channel or bladder more flexibleand, as the spacers can slide against each other, enables the bladderand channels to conform readily to curved surfaces.

The spacers are preferably made from the same material as the bladdersor channels and are preferably about 4 mm wide and 0.4 mm thick andarranged in opposing pairs.

In FIG. 1 the wrap of the invention is shown open in plan view with thesurface that will contact the foot in use uppermost. The wrap 2 isgenerally Y-shaped and comprises a first arm 4 provided with a bladder6, which contacts the arch of the foot in use and a second arm 8provided with a bladder 10, which contacts the heel of the foot in use.The first arm 4, the arch arm, is provided at its extremity with onepart of the hook and loop fastening material 12. The second arm 8, theheel arm, is provided at its extremity with one part of a hook and loopfastening material 14. The heel bladder 10 and the arch bladder 6 arelocated close to the junction of the arms but may be repositionable onthe wrap by the use of hook and loop fastening material.

In the wrap of FIG. 1 the bladders 6, 10 are constructed from an outerwall, which is welded to the wrap and an inner wall 18, 20 welded to theouter wall. Pneumatic fluid, usually air, is supplied to the bladdersthrough channels 22 formed by spacers 23 on both the inner and outerwalls which abut when the bladder is in a deflated state, best seen inFIG. 7.

The channels 22 run across the fork in the Y and are terminated by aconnector 24, which attaches to a conduit (not shown) and a controlunit. Alternatively, the channels can be elongated further still andconnect directly to the controller. The tail of the wrap 26 is providedon its outer surface with one part of a hook and loop fastening 28 bestseen in FIG. 5.

FIG. 2 shows a single strap embodiment of the wrap of the presentinvention where the heel bladder 30 is integral with a strap 32, whichfastens the device over the instep of the foot. The heel bladder 30 isin two connected parts so that pressure is applied by the bladder oneither side of the posterior tibiofibular ligament. The separation ofthe bladder 30 into two parts may be achieved by a series of welds ofthe inner and outer walls of the bladder, as shown in FIG. 1 at 19. Thewelds are interspersed with spacers to provide a path for fluid flow.Similarly spacers can be provided in any region where a bladder orchannel is likely to kink or block for instance over a bony prominence.

In use, the heel bladder 30 applies pressure to the heel in the mannershown in FIG. 3. In FIG. 3, the heel bladder 30 is shown in an inflatedstate with pressure being applied on either side of the heel.

FIGS. 4, 5 and 6 show the application of the wrap of FIG. 1 to the footof a patient. FIG. 4 shows the first stage of application where thepatient places the arch of their foot over the arch bladder 6, the heelbeing positioned in the fork of the Y. FIG. 5 shows the second stage ofapplication where the tail of the Y 26 is wrapped over the instep of thefoot and the heel arm 8 is lifted up and around the heel of the foot sothat the fastening 14 comes into contact with the fastening 28 on theouter surface of the tail 26. FIG. 6 shows the final stage in applyingthe wrap where the heel arm 4 is folded over the foot to bring thefastening 12 in contact with the fastening 28.

FIG. 6 also shows the positioning of the connector 24 and channels 22 atthe top of the foot, which allows the conduit to be attached to the wrapwithout a tube having to be run down the side of the foot to the archbladder 6 and without a tube having to be run around the edge of thefoot to the heel bladder 10. The channels 22 create a reliable passageof fluid to the bladders 6, 10 without causing pressure points, withoutthe risk of a tube that kinks or collapses, and discreetly, so that anetwork of tubes is not apparent to others. The channels 22 also allowthe patient to wear their ordinary shoes.

The wrap of FIG. 1 allows the patient mobility in their ankle, as thedevice does not restrict hinge or rotational movement of the ankle.

FIGS. 8, 9 and 10 show an embodiment of the invention in the form of anelongate channel 60 where the channel walls 62, 64 are each providedwith a spacing strip 66, 68 attached to the inner surface of each wallso that they abut when the walls 62, 64 are welded together on theirlong sides to form the channel 60. The channel 60 provides a lowerprofile and is more discrete than a conventional tube. The lower profilemeans that the flat channel will not create pressure points against thepatient's limb, when for instance a shoe is worn.

To join the channel 60 to bladder wall 69, the wall 62 is made shorterthan wall 64 as shown in FIG. 8 so that when the walls are weldedtogether to form channel 60 part of wall 64 and strip 68 is leftexposed. The channel wall 64, is folded back at its top edge to exposethe channel interior as shown in FIG. 9. The channel wall 62 is placedon the bladder wall 69 under opening 73 and welded along its upper edge70 to the bladder wall 69. The channel wall 64 is folded up over theopening 73 in bladder wall 69 and welded in place around its free edgesshown as lines 72 in FIG. 10. The welded connection of the air channel60 to bladder wall 69 provides a more secure fluid connection than theuse of conventional tubing and air connectors.

Although the present invention has been shown and described with respectto several preferred embodiments thereof, various changes, omissions andadditions to the form and detail thereof may be made without departingfrom the spirit and scope of the invention.

1. A cuff for providing compression to a limb, the cuff comprising anouter wall joined to an inner wall to form a bladder, the bladder beingprovided with means to separate the walls to maintain a path for fluidflow into and out of the bladder characterised in that the separatingmeans are a spacer provided on the interior of at least one wall, whichseparates the walls when the bladder is deflated.
 2. A cuff as claimedin claim 1 characterised in that the inner wall of the bladder isprovided with a spacer and the outer wall of the bladder is providedwith a spacer which spacers abut when the bladder is deflated.
 3. A cuffas claimed in claim 2 characterised in that the spacer is in the form ofan elongated, flexible strip welded to the bladder wall.
 4. A cuff asclaimed in claim 1 characterised in that the bladder walls areselectively welded to limit the inflation of the bladder in certainareas so that the pressure applied by the bladder is focused on selectedareas of the patient.
 5. A cuff as claimed in claim 1 characterised inthat the bladder walls are welded to create elongate channels for thepassage of air into and out of the bladder, the separating means beingpositioned in the channels.
 6. A cuff as claimed in claim 1characterised in that the cuff is a foot cuff.
 7. A cuff for providingcompression to the foot, the cuff comprising an outer wall joined to aninner wall to form a bladder, and a spacer separating the walls when thebladder is deflated or constricted to maintain a path for fluid flowinto and out of the bladder.
 8. A channel for use in a compressiondevice for connecting one or more bladders to each other or to acontroller, the channel comprising an elongate outer wall joined to anelongate inner wall, the channel being provided with means to separatethe walls to create a path for fluid to flow into and out of the channeland into and out of the bladder.
 9. A channel as claimed in claim 8characterised in that the separating means to separate the walls are inthe form of an elongate, flexible strip welded to the channel wall. 10.A channel as claimed in claim 8 characterised in that the channel isconnected to the bladder by welding.
 11. A channel as claimed in claim 9characterised in that the channel is connected to the bladder bywelding.
 12. A channel as claimed in claim 8 characterised in that thechannel walls are made from the same material as the bladders.
 13. Achannel as claimed in claim 9 characterised in that the channel wallsare made from the same material as the bladders.
 14. A channel asclaimed in claim 10 characterised in that the channel walls are madefrom the same material as the bladders.
 15. A channel as claimed inclaim 11 characterised in that the channel walls are made from the samematerial as the bladders.
 16. A channel for connecting one or morebladders to each other or to a controller in a compression device forproviding compression to a limb, the channel comprising an elongateouter wall joined to an elongate inner wall, the channel being providedwith means to separate the walls to maintain a path for fluid to flowinto and out of the channel and into and out of a bladder.